Microelectronic devices are used in a wide array of products. These devices, such as memory and microprocessor chips and similar devices have traditionally been used in, for example, computers, telephones, sound equipment and other electronic products. Over the last several years, microelectronic devices have become faster, better, and less expensive. Microelectronic devices are accordingly now also used in traditionally non-electronic products, such as appliances, vehicles, toys and games, medical devices, novelty items, etc. The remarkable progress made in the microelectronic device industry has led to improved yet less expensive products of all types. It has also led to entirely new types of products.
A major factor in the development of microelectronic devices has been the machines and methods used to manufacture them. Manufacturing of microelectronic devices requires extreme precision, extremely pure materials, and an extremely clean manufacturing environment. Even tiny particles of dust, dirt, metals, or manufacturing chemicals, at almost any stage of the manufacturing process, can cause defects and failures in devices. These factors had led to the development of specialized machines, manufacturing facilities (or fabs) and manufacturing methods. Due to the costs required to design, build, equip and maintain these types of machines, minimizing out-of-service or downtime (i.e., when a machine is being repaired, serviced, or replaced) is essential.
Modern wafer processing machines typically have multiple processing units or chambers. A significant disadvantage with repairing or maintaining existing wafer processing machines is that the entire machine must often be taken offline for an extended period of time to remove and replace even a single processing chamber. When a processing chamber is removed from the machine for repair, maintenance or service, another replacement processing chamber can be mounted in the machine relatively quickly. However, the robot(s) which precisely move wafers into and out of the processing chambers must be recalibrated to operate with the new processing chamber. Recalibration is necessary to insure that the robot moves to appropriate precise locations, to place or remove wafers. Recalibration is a time-consuming process that increases the downtime for repairing or maintaining processing machines or systems. As a result, when only one processing chamber requires service or does not meet specifications, it is often more efficient to simply continue operating the machine, without using the one out-of-specification processing chamber, until additional chambers also need service, or some other event in the fab provides an opportunity to service the machine without interrupting production. The loss of throughput of a single processing chamber, therefore, is not as severe as the loss of throughput caused by taking the machine offline to repair or maintain a single processing chamber.
However, using the machine with less than all of the processing chambers in operation effectively increases the operating costs of the machine and slows down production of wafers.
Manufacturing of microelectronic devices involves using various chemicals. These chemicals are typically in liquid form, although gases and vapors are also often used. These chemicals must be highly pure and are therefore expensive. Chemicals used in some processes, such as strong acids or oxidizers, are also toxic. Use of these chemicals, and disposal of the chemicals after they are used, can be time consuming and expensive. Consequently, reducing the amount of chemicals used is highly advantageous.
Various techniques have been used to reduce downtime of machines and systems in wafer manufacturing, and to reduce consumption of chemicals. While these techniques have met with varying degrees of success, engineering challenges remain in trying to make further improvements. Accordingly, it is an object of the invention to provide better systems and methods for processing workpieces or wafers.